In the manufacture of carpeting and similar web materials, it is frequently desirable to apply dyes to the web surface in the form of random speckled patterns. For this purpose, it is known to utilize rotating disk distributors, arranged to discharge droplets of liquid dye stuff from the peripheral edge of the disc, by centrifugal force. In the arrangement of the Plotz, U.S. Pat. No. 3,903,715, for example, discs are arranged horizontally over a travelling web of carpet material, and the droplets of dye liquor are discharged horizontally from rotating distribution discs and are allowed to fall by gravity onto the surface of the moving carpet web. A somewhat different arrangement is illustrated in the Norton U.S. Pat. No. 4,338,876, in which distributor discs, rotating about vertical axes are arranged adjacent a vertically moving web of material, such that the centrifugally discharged droplets are impelled against the fabric surface by reason of their discharge velocity.
A shortcoming of known arrangements for the random speckled coating of carpeting and other web materials lies in the inability to achieve a desirable level of randomness in the overall design. Typically, the web material being processed is relatively wide, and several dispensing discs are required to cover the full width of the material. These necessarily are arranged so that the areas of coverage of adjacent distributing devices overlap somewhat and, with conventional equipment, there is sufficient regularity in the "random" distribution, that there is a streakiness to the finished product.
The present invention is directed to improvements in equipment and techniques for the application of dye liquid to carpeting and other web materials in a random, speckled pattern, whereby to significantly improve the true randomness of the application and to significantly minimize any tendency towards streaking because of overlapping coverage. To this end, random distribution of a speckled dye pattern across the full width of a moving web is provided by means of a large number of closely spaced, rotating distribution discs, arranged for rotation about vertical axes. Pursuant to the invention, the rotating discs are of a highly irregular peripheral contour, so that there is wide variation in
the radial and tangential velocity of individual droplets of dye liquor discharged from different areas on the rotating discs. In addition, the sizes of the individual droplets of dye liquor will vary as a function of the disc radius at the point of discharge of the droplet. Accordingly, there is introduced a highly desirable degree of randomness in droplet sizes, as well as in the distribution. For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiments of the invention, and to the accompanying drawings.